Can I be covered by my parent's FSA and my spouse's HSA in the same year / at the same time?

[norafrentress]

I am under 26 and covered by my parent's health insurance and FSA. My fiance has an HSA. Is there a tax problem with me staying on the FSA once we are married if my spouse continues with his HSA? Can he contribute the family amount to his HSA once we are married?

[Opus 17]

Generally, an FSA will disqualify you from contributing to an HSA.  However, this FSA is somewhat special.  Your parent's FSA can cover your expenses but not your spouse's expenses.  Therefore, your spouse is not considered to have "other medical insurance coverage", and she can contribute to an HSA in her name, using either the single or family limit, depending on what kind of HDHP coverage she has.

Separately, an HSA can always be used to pay for qualified medical expenses for the account owner, a spouse, or the owner's dependents.  It doesn't matter how the money got in the account or what kind of insurance you have at the time the medical expense is incurred; once money is in the account it can be used to pay any qualifying expenses.

The rule about having other insurance coverage disqualifies the covered person from making tax-deductible contributions to an HSA but it does not disqualify paying for expenses out of already deposited funds.

[dmertz]

Unless your spouse has family HDHP, he will be eligible to contribute only up to the limit for self-only HDHP coverage.  If your spouse has family HDHP coverage on December 1, 2018, your spouse will be eligible to contribute the full-year family limit based on the last-month rule, but must then maintain that coverage throughout 2019 to avoid a 10% additional tax for failure to remain an eligible individual throughout the testing period.